It is known that for fixing ducts or pipes for carrying petrol to a frame or underbody of an automobile, clamp-type retention elements are used, which comprise a supporting body having a contrast surface, means for fixing the ducts on the supporting body and hooking means designed to keep the contrast surface in contact with the frame.
The supporting body comprises a first jaw bearing the contrast surface and a second jaw, shaped like a clamp, which, together with the first jaw, defines, in a closing position, a housing seat for a portion of an axisymmetrical duct or pipe.
To enable fixing of ducts or pipes having different diameters, the fixing means comprise flexible projecting elements, carried by the supporting body in a position corresponding to the seats. The known flexible projecting elements are arranged on a side wall, which delimits the through seat, and extend in cantilever fashion towards the inside of the seat in a direction transverse with respect to the axis of symmetry of the axisymmetrical duct.
Consequently, when the first and the second jaws are closed, the projecting elements come into contact with the duct or pipe, bend, and exert an elastic action, which, on the one hand, tends to compensate for a certain variation of diameter of the duct or pipe and, on the other hand, has the purpose of retaining the component in the seat, substantially without allowing any vibrations.
However, the aforesaid elastic projecting elements do not adapt easily to the retention of components having diameters that are very different from one another. On the one hand, if they are made with a low stiffness, they adapt more easily for retaining components of different diameters but, on the other hand, may allow excessive vibrations. If, instead, they are made with a high stiffness they become unsuitable not only for retaining tubes of even only slightly different diameter effectively but are not even able to adapt easily to the different dimensions of tubes with the same nominal diameter (due to the constructional tolerances), with possible generation of noise. In the worst cases, they can even hinder a correct flow of fluid, restricting the cross section of the duct or pipe to be retained.
Furthermore said projecting elements can lead to relatively large overall dimensions in a radial direction, in so far as they are housed between the side wall of the housing seat and the duct or pipe and in use are set between the duct or pipe and the side wall itself.